Restricted Hydrolysis of Newly Replicated DNA in Isolated Nuclei from Yosbida Sarcoma Cells

Akiyoshi, Hiroto

doi:10.1093/oxfordjournals.jbchem.a133634

Cited by 3 publications

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“…Therefore, understanding of chromosome structure should be increased by clarifying the enzymatic properties of nuclear acidic DNases as well as their modes of actions in situ in comparison with those of other nuclear deoxyribonucleases. Newly synthesized DNA was also effectively hydrolyzed under acidic conditions without divalent cations in isolated nuclei (1). This can again be explained in terms of the peak A or peak B activity from its nonspecific properties.…”

Section: Discussionmentioning

confidence: 82%

“…The preferential inhibition of the exonuclease by mononucleotide, a proofreading exonuclease inhibitor, contributes to this conclusion. These properties indicate that it is this peak enzyme that performed the restricted hydrolysis of newly replicated DNA in isolated nuclei (1). It is likely, therefore, that the deoxyribonucleotide turnover that has observed in isolated nuclei (2, 3) is carried out by this peak enzyme.…”

Section: Discussionmentioning

confidence: 87%

“…Mammalian cell nuclei contain several cation-dependent endonucleases with alkaline pH optima (23,24), a typical one being Ca 2+ -Mg 2+ dependent endonuclease (12). Although these enzymes were reported to produce oligonucleosomal or supranucleosomal DNA fragments (25,26), my previous paper (1) demonstrated that incubation of nuclei under alkaline conditions in the presence of divalent cations did not produce acid soluble materials from internal chromosomal DNA. This finding may indicate that the action of such alkaline DNases on nuclear DNA in situ is different from that of the acid DNases reported in this and the previous paper.…”

Section: Discussionmentioning

confidence: 99%

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Studies on Nuclear Acid Deoxyribonucleases and Proofreading Exonuclease Isolated from Rat Liver Nuclei

Akiyoshi

1988

The Journal of Biochemistry

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Three kinds of deoxyribonucleases (peaks A, B, and C) were separated from purified rat liver nuclei on DEAE-cellulose column chromatography, and their characteristics were partially studied. Peaks A and B had endonuclease activities under acidic conditions with low substrate specificity and did not require divalent metal ions. Peak C had an exonuclease activity under alkaline conditions with substrate specificity for denatured DNA or single stranded homopolymer and required divalent cations. Peak C degraded 3'-terminally mismatched substrate much faster than 3'-terminally matched substrate.

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Section: Discussionmentioning

confidence: 82%

Section: Discussionmentioning

confidence: 87%

Section: Discussionmentioning

confidence: 99%

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Studies on Nuclear Acid Deoxyribonucleases and Proofreading Exonuclease Isolated from Rat Liver Nuclei

Akiyoshi

1988

The Journal of Biochemistry

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Conversion of dNTP to dNMP dependent on DNA synthesis in isolated Yoshida sarcoma nuclei

Akiyoshi

1982

Biochimica et Biophysica Acta (BBA) - Gene Structure and Expres

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Inhibition of cell proliferation by interferons

Moore

Gewert

Clemens

1984

European Journal of Biochemistry

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The inhibition of proliferation of Daudi cells in culture by human interferons is characterized by a change in the kinetics of labelling of different size classes of newly synthesized DNA. Initially, labelled precursors are incorporated exclusively into small DNA (Okazaki fragments) in both control and interferon-treated cells, as revealed by alkaline sucrose gradient centrifugation. In the interferon-treated cells, there is enhanced labelling of this small DNA after short periods of incorporation and slower conversion to larger DNA size classes, in comparison with the DNA of control cells. This effect is apparent after 12 h of interferon treatment, coincident with the onset of the inhibition of cell proliferation. It becomes progressively more marked up to 4 days, by which time cell growth has ceased completely.Experiments using bromodeoxyuridine as a density label and analysis of radioactive DNA on caesium chloride/caesium sulphate gradients also reveal that some newly replicated DNA may be unstable and may turn over within a few hours of its synthesis. The label derived from DNA breakdown is efficiently reincorporated into newly synthesized molecules. It is suggested that interferon treatment inhibits DNA replication by activating DNA turnover rather than by directly inhibiting synthesis. This effect, together with the progressive retardation of conversion of Okazaki fragments to larger DNA, may lead to the eventual failure of cell proliferation.Highly purified preparations of mammalian interferons have been shown to exert multiple biological effects on their target cells. In addition to the widely studied inhibition of viral replication, the anticellular actions of both naturally occurring [I -31 and cloned interferon species [4] are of considerable interest. There is, however, very little information concerning the molecular mechanisms by which the replication of the cellular genome is regulated during growth inhibition by interferons. Some studies have suggested an inhibition of DNA synthesis, based on impaired incorporation of [3H]thymidine, but at least in some cases this reflects severely impaired thymidine uptake and thymidine kinase activity rather than a true effect on DNA replication [5 -81. We are carrying out a detailed analysis of the changes in cellular functions which may be responsible for the antiproliferative effect of human interferons on Daudi cells in culture.Daudi cells are human lymphoblastoid cells containing multiple copies of the Epstein-Barr virus genome. They are highly sensitive to the inhibitory effects of interferons on cell growth [7, 9-111 and treatment with 100 units/ml of a-interferons causes a 40 -50 % inhibition in the rate of cell proliferation after two days [8]. There is, however, no more than a 10 -15 % inhibition of the overall rate of DNA synthesis per lo6 cells after this period of treatment, as measured by flooding the intracellular dTTP pool with excess labelled thymidine or by assessing incorporation of [3H]dCTP into DNA in permeabilized and lysed cell systems [I...

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Restricted Hydrolysis of Newly Replicated DNA in Isolated Nuclei from Yosbida Sarcoma Cells

Cited by 3 publications

References 0 publications

Studies on Nuclear Acid Deoxyribonucleases and Proofreading Exonuclease Isolated from Rat Liver Nuclei

Studies on Nuclear Acid Deoxyribonucleases and Proofreading Exonuclease Isolated from Rat Liver Nuclei

Conversion of dNTP to dNMP dependent on DNA synthesis in isolated Yoshida sarcoma nuclei

Inhibition of cell proliferation by interferons

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